Conventionally, in the image forming apparatus, an unfixed toner image is formed on a recording material, and thereafter, is subjected to a fixing process by a fixing device.
In a fixing device described in Japanese Laid-Open Patent Application No. 2015-59964, at least one of a pair of rotatable members for forming a nip (portion) is constituted by an endless belt.
Further, in this fixing device, a type in which a shift phenomenon of the endless belt is actively controlled is employed. Specifically, a position of the endless belt with respect to a widthwise direction is detected, and, on the basis of this position detection result, one of the rollers stretching the endless belt is inclined (i.e., tilted or swung), whereby the endless belt is reciprocated with a certain range.
When a wax component contained in toner adheres (sticks) to a mechanism for detecting the position of the endless belt, however, a normal position detection is not carried out, so that there is a liability that a situation such that the position of the endless belt cannot be properly controlled arises.